Range of motion after stemmed total hip arthroplasty and hip resurfacing - a clinical study.

Range of motion after total hip arthroplasty is becoming an important topic as today's patients present at a younger age and are more active. An effective study design to carry out comparisons of clinical performance between two implants should eliminate patient-related extraneous variables (e.g., age, gender, activity level, among others). The aim of the present study was to compare the range of motion results achieved postoperatively between metalon-metal hip resurfacing (HR) and conventional total hip arthroplasty (THA) in a cohort of bilateral patients implanted with both designs. Thirty-five patients who had undergone bilateral surgery with one hip receiving an HR device and the contralateral hip receiving a THA were retrospectively selected. Sixty-nine percent of the patients were male, and at the time of implantation of the resurfacing device the mean age of the patients was 53 years. The mean follow-up time was 88 months for the hips treated with HR and 96 months for the hips that received a THA. We found no difference in any of the range of motion measurements between HR and THA even after separating the cohort into two groups based on the femoral head size of the THA (femoral heads under 40 mm and femoral heads greater or equal to 40 mm). Our investigation showed that, for most patients, prosthetic design is unlikely to be a limiting factor of range of motion after surgery provided that the positioning of the acetabular component is adequate.